I think this is the first help update after the Flash Updater 7.2 release. Most would have noticed but then as nobody is blogging, some might have missed the same. Flash MX 2004 help have an update on September 8, 2004 according to the help changelog record.
Some of the notable updates are that of

* Using Flash > Creating Motion > Tweening instances, groups and type.
* JSAPI's Element Object
* DateField.close in Using Components
* And many other updates in the Actionscript Language Reference